Time Travel

Use a simple analogy to understand how a time machine might work. Unlike movie scenarios featuring dematerializing and rematerializing, a real time machine would be a spaceship that moves through all the intervening points between two locations in spacetime. Also explore paradoxes of time travel.

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Begin your study of the physics of time with these questions: What is a clock? What does it mean to say that "time passes"? What is the "arrow of time"? Then look at the concept of entropy and how it holds the key to the one-way direction of time in…

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In the rolling hills of Ireland's County Tipperary, a laborer harvesting peat from a dried-up bog spots the remnants of a corpse and stops his machine just in time, revealing a headless torso almost perfectly preserved and stained dark brown by the bog. Archeologists recognize the corpse as one of…

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We can't directly see the forces that govern Earth, but we can see their shadows in the shapes of nature that surround us. If we understand why these shapes exist, we can understand the rules that bind the entire universe.